Why didn't Umar ibn al-Khattab pray over the Prophet (peace be upon him) when the Prophet mentioned the Qudsi Hadith: "That was Gabriel who came to teach you your religion"?

The scholars have not found a specific reason for the infrequent mention of blessings and peace upon the Prophet (peace be upon him) in the words of the Companions. This might be one of the arguments for those who do not consider it obligatory to send blessings upon him when he is mentioned. The obligation of sending blessings upon the Prophet (peace be upon him) when his name is mentioned is a matter of scholarly disagreement, and the opinion of it being recommended has stronger evidence. Ibn Hajar mentioned in "Fath al-Bari" ten different scholarly opinions regarding the ruling on sending blessings upon the Prophet (peace be upon him), ranging from it being recommended, to being obligatory once in a lifetime, or during prayer, or every time he is mentioned repeatedly, or in every gathering, or in every supplication.